To effectively treat these areas you need to penetrate surface pores with something that will kill the organism while removing any available nutrient or residues, which might harbor or provide food for the mold. Hot moist steam at temperatures of 220 to 230 degrees Fahrenheit. will penetrate far deeper into all substrates, destroy the mold organism while at the same time remove surface soils that feed the mold. This is a very green process, using only tap water – not chemicals. Your results will be visibly superior and will prevent the return of the mold for up to six or eight weeks. This period can be extended indefinitely with a quick periodic cleaning using a steam vapor system.Superheated steam by definition will provide a fine water mist or vapor, that carries with it energy in the form of heat. You will not be needing offensive smelling chemicals, or be exposing yourself or any building occupant to what may be a toxic or discomforting chemical residue. Nor will you damage the substrate you are treating. In fact, the surface will be easier to clean in the future because you have not degraded the surface. As an added bonus, the restroom will smell fresher when you are done because the organisms which produce the lingering odors will be gone as well.Most molds spread by... — Rick Hoverson, Advanced Vapor Technologies, LLC425-775-9000